1. Technical Field
This invention relates generally to methods, systems and apparatus for managing digital communications systems.
2. Description of Related Art
Digital subscriber line (DSL) technologies provide potentially large bandwidth for digital communication over existing telephone subscriber lines (referred to as loops and/or the copper plant). In particular, DSL systems can adjust to the characteristics of the subscriber line by using a discrete multitone (DMT) line code that assigns a number of bits to each tone (or sub-carrier), which can be adjusted to channel conditions as determined during training and initialization of the modems (typically transceivers that function as both transmitters and receivers) at each end of the subscriber line.
In DSL systems, crosstalk that occurs among the twisted pairs typically reduces and/or limits performance. It is known that joint processing of signals transmitted and/or received by a group of lines (commonly described as “vectoring”) can assist in reducing crosstalk. In some cases, the joint signal processing among the group of lines is performed at the receiver side only (for example, in cases where the transmitters of the lines belonging to the group are geographically dispersed), which is the case for some DSL upstream communication. The joint receiver signal processing often is described as generalized decision feedback equalization.
Systems, apparatus, methods and techniques that provide improvements for implementing generalized decision feedback equalization would represent a significant advancement in the art. Also, systems, apparatus, methods and techniques for implementing such equalization that can adapt dynamically to changing line conditions likewise would represent a significant advancement in the art.